Effects of environmental factors on odor emission from pig manure

Altering environmental factors may change odor emission from pig manure. The main objective of this laboratory-scale study was to examine the effects of temperature, ventilation rate, emitting area, and manure dilution ratio on odor emission from growing pig manure, while also testing their effects on manure characteristics. Manure was placed in vessels with different surfaces (303, 475, and 595 cm(2)), and water was added to create different dilution ratios (0%, 50%, and 100%). The vessels were connected to glass capillaries with different ventilation rates through the headspace (0.5, 1.0, and 1.5 L min(-1)) and were placed in climate-controlled rooms with different temperatures (10 degrees C, 20 degrees C, and 30 degrees C). We used a face-centered central composite design with 54 experimental units in two rounds of three blocks. Odor samples were taken at the end of experiment (after seven days). Manure samples were collected at the start and at the end of the experiment. The mean odor emission from the manure vessel was 2326 ou(E) h(-1) m(-2). Increased temperature, ventilation rate, and dilution ratio increased odor emission. Emitting area did not influence odor emission, but positively influenced total-N loss. Total-N loss increased as temperature and ventilation rate increased, but decreased as dilution ratio increased. Lowering temperature and ventilation rate can be considered as starting points to reduce odor emission from pig manure in practical conditions. The effects of dilution ratio and emitting area on odor emission could not be fully separated from the effect of headspace volume in this study and should be further studied.